Abstract
Synchronization of the secretory cycle in vivo was obtained by injecting isoprenaline as an inducer of secretion. A quantitative correlation between enzyme release, its subsequent reaccumulation, and the sequence of ultrastructural changes was found. At the ultrastructural level secretion was paralleled by depletion of zymogen granules through fusion of the granule membrane with the lumen membrane and discharge of the content. Each zymogen granule membrane, once connected with the lumen, acted as a lumen membrane. Fusion was thus sequential and resulted in a dramatic enlargement of the lumen space. During the entire process the passage between the lumen and the intercellular space remained blocked by the tight junctions, as shown by their impenetrability to ferritin. Reduction of the lumen size following enzyme discharge seemed to be achieved by withdrawal of lumen membrane in the form of small smooth vesicles which appeared mostly in the apical part of the cell. At the same time, the cell retracted towards the lumen, the whole process being completed within 2 hr from onset of secretion. Disappearance of the smooth vesicle followed, concomitant with formation of many condensing vacuoles and appearance of mature zymogen granules. The fate of the zymogen granule membrane, including its fusion with the lumen membrane, resorption in the form of small smooth vesicles, and its eventual reutilization mediated by the Golgi system, is discussed.
Full Text
The Full Text of this article is available as a PDF (3.5 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- BDOLAH A., SCHRAMM M. THE FUNCTION OF 3'5' CYCLIC AMP IN ENZYME SECRETION. Biochem Biophys Res Commun. 1965 Feb 3;18:452–454. doi: 10.1016/0006-291x(65)90730-8. [DOI] [PubMed] [Google Scholar]
- Babad H., Ben-Zvi R., Bdolah A., Schramm M. The mechanism of enzyme secretion by the cell. 4. Effects of inducers, substrates and inhibitors on amylase secretion by rat parotid slices. Eur J Biochem. 1967 Mar;1(1):96–101. doi: 10.1111/j.1432-1033.1967.tb00049.x. [DOI] [PubMed] [Google Scholar]
- Bruns R. R., Palade G. E. Studies on blood capillaries. II. Transport of ferritin molecules across the wall of muscle capillaries. J Cell Biol. 1968 May;37(2):277–299. doi: 10.1083/jcb.37.2.277. [DOI] [PMC free article] [PubMed] [Google Scholar]
- CARO L. G., PALADE G. E. PROTEIN SYNTHESIS, STORAGE, AND DISCHARGE IN THE PANCREATIC EXOCRINE CELL. AN AUTORADIOGRAPHIC STUDY. J Cell Biol. 1964 Mar;20:473–495. doi: 10.1083/jcb.20.3.473. [DOI] [PMC free article] [PubMed] [Google Scholar]
- FARQUHAR M. G., PALADE G. E. Junctional complexes in various epithelia. J Cell Biol. 1963 May;17:375–412. doi: 10.1083/jcb.17.2.375. [DOI] [PMC free article] [PubMed] [Google Scholar]
- ICHIKAWA A. FINE STRUCTURAL CHANGES IN RESPONSE TO HORMONAL STIMULATION OF THE PERFUSED CANINE PANCREAS. J Cell Biol. 1965 Mar;24:369–385. doi: 10.1083/jcb.24.3.369. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jamieson J. D., Palade G. E. Intracellular transport of secretory proteins in the pancreatic exocrine cell. I. Role of the peripheral elements of the Golgi complex. J Cell Biol. 1967 Aug;34(2):577–596. doi: 10.1083/jcb.34.2.577. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Konijn T. M., Van De Meene J. G., Bonner J. T., Barkley D. S. The acrasin activity of adenosine-3',5'-cyclic phosphate. Proc Natl Acad Sci U S A. 1967 Sep;58(3):1152–1154. doi: 10.1073/pnas.58.3.1152. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LUFT J. H. Improvements in epoxy resin embedding methods. J Biophys Biochem Cytol. 1961 Feb;9:409–414. doi: 10.1083/jcb.9.2.409. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PARKS H. F. Morphological study of the extrusion of secretory materials by the parotid glands of mouse and rat. J Ultrastruct Res. 1962 Jun;6:449–465. doi: 10.1016/s0022-5320(62)80002-1. [DOI] [PubMed] [Google Scholar]
- PARKS H. F. On the fine structure of the parotid gland of mouse and rat. Am J Anat. 1961 May;108:303–329. doi: 10.1002/aja.1001080306. [DOI] [PubMed] [Google Scholar]
- Robinovitch M. R., Sreebny L. M., Smuckler E. A. Preservation of the secretory granules of rat parotid gland for electron microscopy. Exp Cell Res. 1966 Jun;42(3):634–639. doi: 10.1016/0014-4827(66)90275-8. [DOI] [PubMed] [Google Scholar]
- Robison G. A., Butcher R. W., Sutherland E. W. Adenyl cyclase as an adrenergic receptor. Ann N Y Acad Sci. 1967 Feb 10;139(3):703–723. doi: 10.1111/j.1749-6632.1967.tb41239.x. [DOI] [PubMed] [Google Scholar]
- SCOTT B. L., PEASE D. C. Electron microscopy of the salivary and lacrimal glands of the rat. Am J Anat. 1959 Jan;104:115–161. doi: 10.1002/aja.1001040106. [DOI] [PubMed] [Google Scholar]
- STROMBLAD B. C., NICKERSON M. Accumulation of epinephrine and norepinephrine by some rat tissues. J Pharmacol Exp Ther. 1961 Nov;134:154–159. [PubMed] [Google Scholar]